An electrostatic discharge (ESD) event refers to a temporary and abrupt flow of current between two objects of differing electrical potentials. ESD can be a serious issue for solid state electronic integrated circuits (ICs) as large potential changes and instantaneous current flows that occur during the ESD event can damage silicon junctions and oxide insulators. Typically, damage to an IC from the ESD event can diminish the performance of a silicon-based IC, if not render the IC unusable.
A buildup of charge on an object may occur for a variety of different reasons, many of which occur during the manufacturing and assembly of ICs. As a result, ICs may be subjected to inadvertent ESD events prior to assembly and sale. To protect against ESD events, ESD protection schemes are implemented at nodes of the IC that may come in contact with external objects, e.g., nodes coupled to input pins of the IC. These ESD protection schemes seek to prevent the buildup of large electrical potentials within sensitive sections of the IC. In addition, ESD protection schemes can provide alternative pathways for a large current flow that can occur during ESD events. These alternative pathways attempt to steer current around sensitive internal circuits, effectively bypassing the sensitive sections of the IC.